Russia

The accident was caused by a stall, spin and impact with the ground resulting from a combination of the following factors:
1. The decision by the PIC to allow an unqualified and unauthorized outsider (his son) to occupy his duty station and intervene in the flying of the aeroplane.
2. The execution of demonstration manoeuvres that were not anticipated in the flight plan or flight situation, with the PIC operating the autopilot while not at his duty station.
3. Application by the outsider and the co-pilot of control forces that interfered with the functioning of the roll channel of the autopilot (and are not recommended in the A310 flight manual), thus overriding the autopilot and disconnecting it from the aileron control linkage.
4. The copilot and PIC failed to detect the fact that the autopilot had become disconnected from the aileron control linkage, probably because:
- The A310 instrumentation has no declutch warning. The provision of signals in accordance with the requirements of Airworthiness Standard NLGS-3, para. 8.2.7.3., and international recommended practices, could have enabled the crew to detect the disengaged autopilot in a timely manner.
- The copilot and PIC may have been unaware of the peculiarities of the declutching function and the actions to be taken in such a situation because of a lack of appropriate information in the flight manual and crew training programme;
- It was difficult for the co-pilot to detect the disengagement of the autopilot by feel, either because of the small forces on his control column or because he took changing forces to be the result of Eldar's actions;
- The PIC was away from his position and distracted by the conversation with his daughter.
5. A slight, unintentional further turn of the control wheel(s) following disengagement of the autopilot caused a right roll to develop.
6. The PIC and copilot failed to detect the excessive right bank angle, which exceeded operating limits, and were late in re-entering the aircraft control loop because their attention was focussed on determining why the aircraft had banked to the right, a manoeuvre they interpreted as entry into a holding area with either no course line or with a new (false) course line generated on the navigational display.
A strong signal indicating that the aeroplane had exceeded the allowable operating bank angle, taking account of the delay in recognizing and assessing the situation and making a decision, could in this situation have attracted the crew's attention and enabled them to detect the bank at an earlier stage.
7. The aeroplane was subjected to buffeting and high angles of attack because the autopilot continued to perform its height-keeping function even after the actuator declutched and as the right roll developed, until the pilot disconnected it by overriding its longitudinal channel.
8. Inappropriate and ineffective action on the part of the copilot, who failed to disconnect the autopilot and to push the control column forward when the buffeting occurred and the aeroplane entered an unusual attitude (high angles of attack and pitch). These actions, which caused the aeroplane to stall and spin, could have resulted from:
- the presence of an outsider in the left-hand pilot's seat and the resulting delay before the PIC re-entered the aeroplane control loop;
- the less-than-optimum working posture of the copilot, whose seat was pushed back to its rearmost position;
- the occurrence, 2 seconds following the onset of buffeting, of an unintentional pitching up of the aeroplane, which sharply increased the angle of attack and reduced lateral controllability;
- unpreparedness of the crew to act in this situation because of lack of appropriate drills in the training programme;
- temporary loss of spatial orientation in night conditions.

It was determined that the loss of control was the consequence of an excessive accumulation of ice on stabilizers. Information transmitted to the crew regarding weather conditions at destination did not reflect the actual situation and did not mention any icing conditions.

Wrong approach configuration on part of the crew who should initiate a go-around as the aircraft was too high on the glide.

It was determined that the runway surface was contaminated with snow and has not been cleared prior to takeoff. It was also reported that the runway lights and edge markings were not clearly visible due to snow.

The accident was caused by the failure of an aileron control rod. Nevertheless, representatives from Antonov disagreed, stating icing caused the loss of control.

The commission found that the air starter malfunction occurred when the engine was started due to a structural element of the air conditioning system, probably a fragment of the air-to-air radiator (VVR) splitter of engine n°2, hit under the constant pressure flap. This became possible due to the lack of protection against the ingress of foreign objects from the air lines and the low operational reliability of the VVR. A constant supply of air under pressure from the engines operating at a mode close to the nominal through an open damper led to the starter not switching off and the turbine rotor spinning up to off-design speed with the alarm "Dangerous starter speed" being triggered, which was detected by the flight engineer after starting all the engines. Pressing the starter shutdown button did not turn off the alarm. There were no other signs of failure other than the operation of the warning lamp. The crew, believing that the alarm was false, made the wrong decision to take off, which was a consequence of the unwillingness to act in such a situation due to shortcomings in the regulatory documentation, information support, as well as insufficient information content of the starter's technical condition monitoring system in the cockpit. Laying the mains of all three hydraulic systems through the fire-hazardous compartment of the engine n°2 is a constructive disadvantage of the Tu-154M aircraft.

Engine failure for unknown reasons.